1) Field of the Invention
The invention is in the fields of Piezoelectric Actuators and Cooling Devices for Computing Systems.
2) Description of Related Art
Today's consumer electronics market frequently demands complex functions requiring high power. Power issues become more disconcerting as platforms shrink in size and/or become mobile, e.g. hand-held devices. The cooling issues for such devices may be more complex and significantly different from those for the traditional large form-factor devices such as desk-tops and servers. For example, a cooling system based on forced-air convection may not be the most efficient system for desk-tops and servers, but does enable a compact arrangement for smaller and/or mobile devices.
A piezoelectric actuator-based fan may be used in a forced-air convection cooling system for small and/or mobile electronics devices. FIG. 1A illustrates a cross-sectional view representing a fan having a piezoelectric actuator, in accordance with the prior art. Referring to FIG. 1A, a piezoelectric actuator fan 100 comprises a multi-layer piezoelectric actuator 102 attached to a blade 104. The multi-layer piezoelectric actuator 102 is comprised of alternating conductive electrode layers 106 and piezoelectric layers 108. The crystal morphology of piezoelectric layers 108 changes in response to a voltage being applied across conductive electrode layers 106. As a result, blade 104 is caused to move by way of a tip-to-tip displacement, as depicted by the dashed lines in FIG. 1A. The tip-to-tip displacement can invoke airflow for use in a forced-air convection cooling system.
Unfortunately, using conventional materials (such as Ni, Ag and or Pd for the conductive electrode layer) to fabricate a multi-layer piezoelectric actuator may have its limitations. For example, attempts to increase the tip-to-tip displacement of the blade in a piezoelectric actuator-based fan by adding more alternating conventional conductive electrode layers and piezoelectric layers actually may have the opposite effect. FIG. 1B is a plot of tip-to-tip displacement of the blade in a fan having a piezoelectric actuator as a function of input voltage, in accordance with the prior art. Referring to FIG. 1B, as the number of layers is increased in a multi-layer piezoelectric actuator, the tip-to-tip displacement is reduced at a given input voltage. Therefore, there is a limitation on the tip-to-tip displacement of the blade in a piezoelectric actuator-based fan when using conventional materials to fabricate the conductive electrode layers in the multi-layer piezoelectric actuator.
Thus, a multi-layer piezoelectric actuator with conductive polymer electrodes is described herein.